Vapor generator



Oct. Z0, 19.59 s. N, ARNOLD ETAI- 2,909,158

v VAPOR GENERATOR Filed Jan. 24, 1955 l 5 Sheets-Sheet 1 nventors,SMA/fm2@ M ARA/04@ l @50,965 5 7747-5' (Ittomeg 5 sheetsl-Sheet V2 s.N.' ARNOLD ETA!- vARoR GENERATOR Filed Jan.' 24, 1955 v :inventorsSTANF/zp MAP/v0.40 650/965 T W175i (Ittorneg Oct. 2.0, 1959.

S. N, ARNOLD ETAL VAPOR GENERATOR Filed Jan. 24, 1955 5 Sheets-Sheet 3nventors .STAMP/2.o M ARA/OLD v650,665 E 7247-5 UVM,

Gttorneg tubes.

United States Patent f 2,909,158 IPatented Oct. 20, 1195.9

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VAPOR GENERATOR Stanfield N. Arnld,`Lexington,.Ky., and George E. Tate,

Summit, NJ.,` assignorsjto .Foster Wheeler Corporation, New York, NLY.,a corporation of New York .Application January 24, 1955, Serial No.483,588 v4 claims. ',(cl. 122-235) 'Ihis invention vrelates 'to `vaporgenerators and more particularly to pressure fired vapor generators..Pressure-tired vapor generators, that is, those ired with combustionair'under his pressure, generally comprise a .cylindrical casing inwhich vapor generating tubes are arranged to substantially surround acombustion chamber and to extend substantiallyparallel and/or inclined,tothe longitudinal axis of the casing. In a vnumber of pressureiiredvapor generators, some lof the vapor generating tubes line thecombustion chamber in heat exchange relationship with the combustiongases, both by radiation and convection, while the remaining tubes arearranged outside the combustion chamber and are disposed in the path ofilow of combustion gases discharged from the chamber/.as to be heated byconvection alone. The vapor generating tubes, outside the combustionchamber, generally -areaarranged so that the combustion gases pass oversuccessive :tubes or in a direction normal to the axes ofthe .tubes sothat some tubes are subjected to higher .temperature gases .than otherswhereby .nonyuniform heat absorption results.

The present invention contemplates a novel vapor generator whereinmaximum eiliciency of operation is -obtained.

`In .accordance with the present'invention a novel vapor generator isprovided whichheffects, among other things, substantially the sameor..equal heat absorption by each of the vaporv generating tubes. TheVaporgenerator comprises a .'cylindrically shaped boiler casing Which isprovided witha combustion 'chamber lined with vapor generating tubesextendingsubstantially parallel tothe longitudinal .axis of the chamber.is arranged concentric withthe combustion chamber and has disposed-therein circumferentially arranged vapor generating tubes in heatexchange relationship with cornbustiongases which ilow out Aone end .ofthe combustion chamber and in a direction parallel tothe axes .oftheSecond and third annular gas passages are tarranged in the casing incommunication with .the .rstmentioned .gas .passage and have .disposed.therein superheater. and vapor generating tubes, respectively.- TheVthird annular gas ,passage communicates with an economizer- -wh'ic'hreceives combustion gases from .the third passage and conducts the gases.in `:heat exchange relation- "of Figfl;

` Fig?, is a'transverse `section ofthe' boiler .taken along NLFig. it isan elevational' View 'ofthe supe'rheater as- An annular gas passage A .2-sembily of Fig; ..2 and is illustrated apart from the boiler to moreclearly show the .arrangement of tubularelements thereof; and

VFig. 5 is an lelevational view, in section, of the econo mizer of Fig.l.

Referring now to the drawings and more particularly to Fig. l thereofwherein an .embodiment of .the invention is clearly illustrated, thereference numeral 11 generally designates a Vapor generator whichcomprises a cylindrical and horizontally arranged liquid and vaporvessel .12, a boiler 13 and .an economizer. `14. A'pair .of parelleldowncomer conduits 15 and .'16 each `have .one end connected to the.lower portion fof drum .12 and .extend toward .boiler 13. Conduits 15and 16Iare connected at intermediate portions by a transverse conduit 17to which is connected one end of a `downcomer conduit 18. One upper end.of .a downcomer conduit 19 is connected to conduit 15 and asimilar endof .a conduit 20 is connected to downcomerl adjacent to and belowconduit 17. Downcomers .15 and .16 extend vertically along and belowboiler 13 and then run .upwardly through a casing 21 of boiler 13forconnection to a ring-shaped supply header 22 at diametricallyopposite points thereof (Fig. 2). uSupply header 22 is rectangular :inVtransverse cross-section and is disposed at the lower `portion ofcasing 21. Downcomer conduit 18 extends similarly as conduits 15 and 16but projects centrally through casing 21 for .connection to aring-shaped header .23 arranged within the space 4encompassed by header22. Header 23 is provided with a circular wall'24 which .separates .theheader into an inner chamber 25 and an outer chamber 26. yOpenings 27are provided in wall 24- to communi- Cate chamber 25 with chamber 26.Headers 22 and 23 .are joined together by an annular strip 23 which isfastened to both headers, as for example, by welding.

A circular wall or partition 29xis disposed in casing 21 coaxial withthe longitudinal axis of the latter .and extends from the upper portionofthe casing downwardly to .a point above headers22 and 23 to denne a`furnace or combustion chamber 30. A substantially cone-shapedrefractory :member 31 is disposed below the lower edge of wall 29 Itodefine .a oor Ifor the furnace. A plurality of upright boiler or vapor.generating tubes 32 line the sidek of wall 29, facing the furnace, andare connectedat their lower -ends to header 23. Tubes 32 extend from thecombustion chamber to below the lower edge of wall 29 and then runsubstantially parallel to the sides of oor 31 to separate into threeseparate, circumferential and .concentric rows 33, 34, and 35. Tubes 32of innermost row 33 are connected to chamber 25 .of header ..23 whiletubes 32 of rows 34 and 35 are connected to cham- .ber 26. The portionsof tubes 32 in combustion chamber 30 are substantially in contact witheach other except between the lower edge of wall 29 and furnace floor 31where the tubes of rows 33 and 34 are bent away from the tubes of row 35toward the axis of the furnace to provide spaces for `passage of.combustion gases from the .combustion chamber; the space between thelower .edge of wall 29 and furnace Ifloor 31 defining a gas outlet 36.for discharging combustion gases from the furnace. Theupperends offurnace tubes 32 are connected ,to a circular header Y37,` formed incasing 21, and the header is .connected to liquid and vapor vessel 12 bya plurality of riser conduits v38.

An yinlet conduit 39 is Yconnected to a source of combustion vsupportingfluid (not shown) under Vpressure and to .the upper portion of casing 21and centrally thereof, and communicates with a chamber 40 within .casing.21.

Chamber 40 has a plurality of vanes 41 disposedy therein,

adjacent outlets 42 formed in the lower portion of the chamber wherebythe combustion supporting fluid under pressure, entering chamber 40 isdischarged through outlets 42'and given a swirling motion about the axisof the furnace. A fuel conduit 43 connected to a source of fuel (notshown) extends through conduit 39 and chamber 40 to terminate in atiring nozzle 44 at the bottom vof chamber 40. The fuel for firingcombustion chamber 30 is a iiuid, as for example, oil and the combustionsupporting fluid may be air or oxygen.

A second circular wall or partition 45 is disposed in casing 21 and isspaced from and concentric with wall 29. Wall 45 extends upwardly fromadjacent header 22 and together with wall 29 deiines a circular orannular -gas passage 46 for receiving gases discharged through gasoutlet 36. A plurality of primary convection tubes 47 are arranged ingas passage 46 in directions parallel Vto .tubes 32, and are dividedinto two circumferential rows, one row being arranged adjacent wall 29and the -second row being arranged adjacent wall 45; the rows of tubes47 being spaced apart to provide passage of gases therebetween. Some ofthe tubes 47 in the row adjacent wall 45 and above the upper edge of thelatter are bent to provide for passage of gases from gas passage 46while some of the tubes 47 of the row of tubes adjacent wall 29 arebentto provide for passage of gases from combustion chamber 30 into gaspassage 46. The lower ends of tubes 47 are connected to header 22 andthe upper ends of the tubes are connected to a circular header 48 formedin the upper portion of the casing 21, which header is arrangedconcentric with header 37. Header 48y is connected to liquid and vapordrum 12 by a plurality of riser tubes 49. An inclined battle 50 isprovided across tubes 32 and 47, adjacent furance oor 31, to prevent thepassage of gases from chamber 30 toward headers 22 and 23.

A third circular wall or partition 51 is disposed in casing 21 and isarranged concentric with walls 29 and 45 to define with the latter asecond circular or annular gas passage 52. A superheater assembly 53 isdisposed in gas passage 52 and comprises helically wound superheatertubes 54, arranged in tive concentric rows or`V tube, a single complete360 degrees turn of each of eleven tubes is provided, whereby each ofthe layers includes twelve tubes. l The invention is not to be construedas limiting each of the layers to the above number of helical tubes butrather the number is dependent upon design .f

considerations. Furthermore, the length of the tubes in thediiferentlayers is not the same because the length of the tubes of a particularlayer is a function of the diameter and height of said layer. Asuperheater tube 54A of outermost layer 59 is shaded in Fig. 4 to moreclearly illustrate the pitch of the tubes and the number of tubes inbetween each pair of convolutions.

Layer 55 surrounds substantially the entire outside surface of wall 45to cool the latter during operation of the vapor generator whereas layer59 lines substantially the entire inside surface of wall 51 for coolingpurposes also. As is more clearly shown in Fig. 4, the end portions ofeach of the superheater tubes are bent substantially at right angles tothe intermediate portion of its respective tubes and extend in verticaldirections. The lower end portions of tubes 54 are connected to aringshaped inlet superheater header 60, rectangular in crosssection,which is disposed concentric with supply headers 22 and 23, and theupper end portions of the superheater tubes are connected to a similarVshape outlet superheater header 61 disposed in the upper portion ofcasing 21. A plurality of connecting conduits 62 communicate inletheaderV 60 with an inlet manifold 63 which is connected to vapor andliquid vessel 12. A conventional battle-type dryer 64 is arranged invessel 12 for removing moisture from the vapor in the latter andcommunicates with inlet manifold 63 to provide the latter with substan-4 tially dry vapor. A plurality of connecting conduits 65 are connectedto outlet header 61 and project outside casing 21 to communicate header61 with a superheated vapor outlet conduit 66.

A plurality of upright vapor generating or secondary convection tubes 68are arranged circumferentially in a third circular or annular gaspassage 69, substantially dened by wall 51 and a wall 69A next to casing21. Gas passage 69 communicates at its lower end with passage 52 toreceive combustion gases therefrom and with a casing lgas outlet 70(Figs. l and 2) for discharging combustion gases from the casing. Thelower ends of ,vapor generating tubes 68 are connected to a circularinlet header 71, formed in casing 21, and the header is connected to thelower ends of tubes 19 and 20. The upper ends of vapor generating tubes68 are connected to a circular outlet header 72, formed in the upperportion of casing 21, and the header is connected to vapor and liquiddrum 12 by a plurality of-vertically disposed riser conduits 73.

Economizer 14 (Figs. 1 and 5) comprises a vertical casing or shell 75and has disposed therein three vertically arranged and concentriccylindrical walls or partitions 76, 77 and 78, respectively. Partition76 provides a gas passage 79 while partition 77 cooperates withpartition 76 to define a gas passage 80. Partition 77 cooperates withpartition 78l to dene a gas passage-81 and partition 78 cooperates withthe inner surface of casing 75 to define a gas passage 82. A group ofhelically arranged tubes 83 are disposed in gas passage 80 and arearranged in the same manner as the superheater tubes 54 in casing 21. Inthe case of tubes 83, the tubes are arranged in seven concentric rows orlayers and the pitch of the helices of the tubes are such that seventubes are provided between each pair of convolutions of a particulartube. The lower portions of tubes 83 are bent substantially at rightangles to the intermediate portions of the tubes and are connected to aring-shaped feed liquid inlet header 84 which in turn is connected to afeed liquid inlet conduit 85. Conduit 85 projects through the bottom ofcasing 75 and is connected to a source of feed liquid (not shown). Theupper end portions of tubes 83 are bent in the same manner as the lowerends and are connected to an upper ling-shaped outlet header 86 disposedin gas passage 80 and in alignment with lower header 84. A second groupof helically wound tubes 87 aredisposed in gas passage 81 and compriseeight concentric layers with six tubes between each pair of convolutionsof a particular tube. The lower ends of tubes 87 are connected to aring-shaped inlet header 88, arranged concentric with header 84 andheader 88 is connected to upper outlet header 86 by a connecting conduit89 which passes centrally of passage 79. The upper end portions of tubes87 are connected to an outlet header 90 arranged concentricwith header86 and in Valignment with lower header 88. A connecting conduit 91 isconnected to outlet header 90 and communicates the latter with aperforated pipe 92 arranged within vapor and liquid vessel 12. A cover93 is arranged at the top of gas passages 80 and 81 and openings 94 areprovided inthe cover.` Cover A93- serves to seal passage 81 from thespace at the top of casing ,'75 while openings 94 serve to communicatepassage 80 with the upper portion of the casing. A cover 95 is providedat the lower edges of partitions 76 and 77 and the cover is formed withopenings to accommodate feed liquid inlet conduitY 85 and a gas outlet97 which communicates with the lower portion of 'gas passage 80. Cover95 servesrto seal gas passage 80 from the space in .the lower portion ofcasing 75. Covers 93 and 95 are each provided with an aligned centralopening to freely communicate both ends of'passage 79 with the upper andlower portions of the casing 75, respectively. A gasoutlet conduit 98 isconnected to the upper portion of casing 75 for. discharging combustiongases from the casing.. A'damper or valve 99 is proganarse vided inconduit 98 and is voperable for controlling the flow of combustion gasesfrom the casing. A second valve 100 (shown only in Fig. 1) is connectedin outlet conduit 97 for controlling the flow of gas through theconduit. Conduits 97 and 98 may be connected to further heat recoveryapparatus, or connected for discharging to the atmosphere as desired.

In operation, combustion supporting `fluid, as for ex- 'ample air oroxygen, under pressure is delivered through conduit 39 and chamber 40whence it passes into combustion chamber 30 in a swirling stream. At thesame 'time a fluid fuel, as for example, oil is delivered through feedconduit 43 and through ring nozzle 44 where the fuel is atomized andthence projected into the swirling combustionair for intimate mixturewith the latter. The fuel air mixture is then 'ignited whereby gases ofcombustion are formed in the combustion chamber and the gases .pass outof the latter through the lower end of the chamber at gas dischargeoutlet 36. The combustion gases flow upwardly in gas passage 46 in heatexchange relationship with vapor generating tubes 47. Thecombustiongases are discharged from the upper portion, or end, of passage 46 andthen the gases flow downwardly in gas passage 52 and over superheatertubes 54 in heat exchange relationship with the latten From gas passage'52 the combustion gases flow upwardly in passage 69 in heat exchangerelationship with vapor generating tubes 68. The gases in passage 69then ow out of the latter at the upper portion thereof and aredischarged from the casing through gas discharge outlet 70.

Heated feed liquid, as for example, water is delivered to vapor andliquid vessel 12 through conduit 92. The water in vessel 12 ows throughdowncomer conduits 15 and 16, thence linto transverse conduit 17 andconduit 1S, and in connecting -conduits 1'9 and 20. The water in conduit18 is conducted into chambers V25 and 26 of Yheader 23 thence throughtubes 32 where part of the Vwater is changed to steam. The steam inboiler tubes 32 passes into header 37 whence it is conducted throughriser tubes 38 into vessel 12 where the steam is collected in the `vaporspace of the vessel. 'I'he water in conduits 15 and l'passes :into'header .22, thence through tubes 47, whence the steamgenerated thereinpasses into header 48 and into vessel 12 by way' of riser tubes 49. Thewater Ain conduits 19 Vand .28 passes into circular header 71 `andthence into tubes 68 where steam is generated. The steam from tubes `68-passes into outlet header 72 whence itis conducted through riser tubes73 to the vapor space of the vapor and liquid vessel 12. The steam invessel 12 passes through dryer 64 where most of the moisture is removed,thence -into superheater inlet manifold 63 whence Vit is conducted toconnecting conduits 62. The steam from conduits 62 passes intosuperheater inlet header 60, thence through tubes'54 of superheaterassembly S3 where the steam is superheated by the combustion gasespassing over the tubes. The superheated steam then passes out of thesuperheater assembly and into outlet header 61 whence the superheatedsteam is conducted by tubes 65 into superheated steam outlet conduit 66.

It will now be apparent that the vapor generator of the presentinvention provides for uniform heat absorption by the vapor generatingtubes by reason of the ilow of combustion gases in a direction parallelto the longitudinal axes of the vapor generating tubes. Since the heatinput to or heat absorbed by the vapor generating tubes of acircumferential row is substantially equal and the length of said tubesare also substantially equal, uniform ow of iluids in the tubes isprovided whereby distributing plugs, generally employed in vaporgenerators where the flow is unequal, are not required in the presentinvention. Furthermore, the arrangement of helical superheater tubes inthe present invention provides for more simple structure in that lesssuperheated tubes are conduit 7G enter gas passage 81 of economizer 14.and

tlow downwardly in heat exchange relationship with the tubes 87 ofthepassage. The gases in passage 81 are then discharged through the lowerend thereof and flow upwardly'through gas passages `79 and 82 and intothe space at the upper portion of casing 75. Whenfurnace 30 is firedwith an air-fuel mixture, valve 100 in conduit 97 is closed and valve 99in conduit'98 is opened. Consequently, the combustion gases frompassages 79 and 82 pass into the upper space of casing 75 and then lowthrough conduit 98 and past valve 99. On the other hand, when furnace 30is red with an oxygen-oil mixture, valve 99 in conduit 98 is closed andvalve 100 is opened. In such event, the combustion gases from gasdischarge conduit 70 o'w into gas passage 81 kthen downwardly and out ofthe bottom of the latter .to flow upwardly in passages 79 and 82. Thegases in passages 79 and 8I2'then flow into the upper space of casing 75thence through openings94 in cover 93 and downwardly in gas passage l inheat exchange relationship with the tubes 83 therein. The gases inpassage Sil-pass out of the bottom through the openingin .plate 95thence through 4conduit 97 past valve 100. vInthe case of the oxygen-oilfiring of combustion chamber 30, the resulting combustion gases `arepassed through both gas passages 80` and 81 in order to` utilize theheat obtained by condensing the steam in the combustion gas; it beingunderstood -that the oxygen in the combustion gases combines with thehydrogen to yield steam. The combustion gases resulting from the firingof the air-oil mixture in chamber 30 are conducted through passage 81only, because most yof the heat of the combustion gases is given up inpassing through passage 81 alone.

Water from the source of feed water-(not shown) is conducted throughfeed liquid conduit 85 into lower header 84. From header 84 the waterpasses -upwardly through tubes 83 in passage 80 and in heat exchangeVrelationship withrthe gases flowing therethrough. vThe heated feedwater from tubes 83 in passage "80 is then collected in upper header 86whence the lWater .passes through conduit 89,-in passage 79, and intolower circular header 88. Feed water in header 88 is then conductedthrough tubes 87 of Apassage V81 whence it is collected in .header 90.`Conduit 91 conducts the water'from header and-delivers vit intoperforated pipe 92 in drum 1'2 Land thereafter the water flows into thedowncomer conduits.

.1t will now be lapparent that the vapor generator. ofy the presentinvention provides a novel `economizer which :is adapted-for maximumefficiency both in the scase ofthe firingof air-oil mixture in chamberS0 andfoXygen-oil tiring in the chamber. In either case optimumutilization of the heat contained in the combustion gases from chamber30 is effected.

Although one embodiment of the invention has been illustrated anddescribed in detail, it is to be expressly understood that the inventionis not limited thereto. Various changes can be made in the design andarrangement of the parts without departing from the spirit and scope ofthe invention as the same will now be understood by those skilled in theart.

What is claimed is:

l. ln a vapor generator of the class described adapted for burning anair-oil mixture and an oxygen-oil mixture, a vapor and liquid vessel, `asubstantially cylindrical casing, means defining a cylindricalcombustion chamber in said casing having a combustion gas outlet, meansfor firing said combustion chamber whereby combustion gases are formedtherein, means forming a first annular gas passage surrounding saidcombustion chamber and communicating with said gas outlet to receivecombustion gases therefrom for travel in a direction parallel to thelongitudinal axis of said combustion chamber, a plurality of vaporgenerating -tubes disposed in said first gas passage and incommunication with said vapor and liquid drum, said vapor generatingtubes being arranged in a direction parallelto said axis of saidcombustion chamber and in heat exchange relationship with the combustiongases flowing in said first gas passage, means forming a second annulargas passage surrounding said iirst gas passage and communicating withthe latter to receive combutiongases for travel therein, a plurality ofvapor conducting tubes disposed in said second gas passage and in heatlexchange relationship with the combustion gases therein, said vaporconducting tubes being in communication with said vapor and liquidvessel to receive vapor therefrom, a casing gas discharge outlet in thecylindrical casing and in communication with said second gas passage toreceive combustion gases therefrom, a second cylindrical casinghaving aninlet in communication with said gas discharge outlet, means forming athird annular gas passage in said second cylindrical casing and incommunication with said inlet, means forming a fourth annular gaspassage in said second cylindrical casing arranged concentric With saidthird gas passage and in communication therewith, a plurality of liquidconducting tubes disposed in said third and said fourth gas passages incommunication with each other and with a source of feed liquid, meanscommunicating saidliquid conducting tubes with the vapor and liquid drumto conduct feed liquid thereto, and means for causing combustion gasesfrom said casing gas outlet to iiow through said third gas passage onlyand preventing flow of combustion gases through said fourth gas passagewhen an air-oil mixture is burned in the Vapor generator.

2. The vapor generator set forth in claim l wherein means are providedfor forming a fth annular gas passage concentric with said third andsaid fourth gas passages and in communication therewith,.and whereinvalve means are provided which are operable in first predeterminedpositions to cause the combustion gases to ow through only said thirdgas passage when yan air-oil mixture is burned, and which are operablein second predetermined positions to cause the combustion gases fromsaid third gas passage to pass successively through said fourth and saidfifth gas passage when an oxygen-oil mixture is burned.

3. In a fluid heat exchange apparatus of the class described, anelongated gas casing having an inlet for receiving heating uid and apair of outlets for discharging heating fluid from said casing, meansforming a rst annular gas passage in communication with said inlet forreceiving heating uid and with one of said pair of outlets, meansforming a second annular passage arranged concentric with said firstannular passage and in communication with the latter and with the otherof said pair of outlets, a plurality of tubes arranged in both saidpassages and in communication with a source of fluid to be heated, Saidtubes being disposed in heat exchange relationship with heating uidpassing through said passages, and control means operable in firstpositions for causing Vheating fluid to pass through said first passageand said one outlet without passing through said second passage and saidother outlet, and operable in second positions for causing the heatinguid to pass through said first and second passages and through saidother outlet only.

4. In iiuid heat exchange apparatus of the class described, an elongatedcylindrical casing having an inlet for receiving heating iiuid and apair of outlets for discharging the heating fluid from said casing,means forming a rst annular passage in communication with said inlet forreceiving the heating fluid and with one of said pair of outlets, meansforming a second annular passage concentric with said first passage andin communication with the other of said outlets, means forming a thirdannular passage concentric with said first and said second passages andcommunicating the latter with each other to provide the second passagewith heating fluid from said first passage, a plurality of tubesarranged in both said first and said second passages and incommunication with a source of fluid to be heated, said tubes beingdisposed in said first and said second passages in heat exchangerelationship with the heating Huid owing through the associated passage,a iirst valve means for said one outlet and movable to a first positionto cover said one outlet and movable to a second position to uncoversaid one outlet, second valve means for said other outlet and movable toa rst position to uncover said other outlet and movable to a secondposition to cover said other outlet, said valve means, when moved totheir respective first positions, causing the heating fluid from saidfirst passage to pass through said third and said second passagessuccesively and out of the casing through said other outlet, and whenmoved to their respective second positions, causing the heating fluidfrom said first passage to ow through said one outlet without passingthrough said second passage.

References Cited in the le of this patent UNITED STATES PATENTS1,684,201 `Pollock Sept. 11, 1928 1,792,327 Schleh Feb. 10, 19311,916,004 Langford June 27, 1933 1,917,275 Rossman et a1. July 1l, 19332,030,265 -Nygaard Feb. 11, 1936 2,201,618 La Mont May 21, 19402,386,188 Artsay Oct. 9, 1945 FOREIGN PATENTS 615,434 Great Britain Jan.6, 1949 l Patent Noo 2,909,158

UNITED STATES PATENT OFFICE CERTIFICATE OE CORRECTION October 1200 1959Stanfield No Arnold et alo It is hereby certified that error appears inthe printed specification of thev above numbered patent requiringcorrection and that the said Letters .Patent should read as correctedbelow.

Column lq line 18, for "under his" read under high Signed and sealedthis 4th day of April 1961(l csEAL) Aft-test: ERNEST w. SWIDER ARTHUR W.cRocKER Attesting Officer v Ading Commissioner of Patents

